6 letter words:
fistic11,
5 letter words:
stiff11,
tiffs11,
4 letter words:
fifi10,
tiff10,
fisc9,
fist7,
fits7,
sift7,
cist6,
cits6,
tics6,
isit4,
3 letter words:
iff9,
fit6,
ifs6,
sif6,
cis5,
cit5,
sic5,
tic5,
its3,
sit3,
tis3,
2 letter words:
if5,
is2,
it2,
si2,
st2,
ti2,